Here’s the full article: https://www.sciencedaily.com/releases/2019/08/190812155502.htm
"Life on Earth arose about 4 billion years ago when the first cells formed within a primordial soup of complex, carbon-rich chemical compounds.
These cells faced a chemical conundrum. They needed particular ions from the soup in order to perform basic functions. But those charged ions would have disrupted the simple membranes that encapsulated the cells.
A team of researchers at the University of Washington has solved this puzzle using only molecules that would have been present on the early Earth. Using cell-sized, fluid-filled compartments surrounded by membranes made of fatty acid molecules, the team discovered that amino acids, the building blocks of proteins, can stabilize membranes against magnesium ions. Their results set the stage for the first cells to encode their genetic information in RNA, a molecule related to DNA that requires magnesium for its production, while maintaining the stability of the membrane.
The findings, published the week of Aug. 12 in the Proceedings of the National Academy of Sciences , go beyond explaining how amino acids could have stabilized membranes in unfavorable environments. They also demonstrate how the individual building blocks of cellular structures – membranes, proteins and RNA – could have co-localized within watery environments on the ancient Earth.
“Cells are made up of very different types of structures with totally different types of building blocks, and it has never been clear why they would come together in a functional way,” said co-corresponding author Roy Black, a UW affiliate professor of chemistry and bioengineering. “The assumption was just that – somehow – they did come together.”"
"The team hypothesized that amino acids might also stabilize membranes. They used a variety of experimental techniques – including light microscopy, electron microscopy and spectroscopy – to test how 10 different amino acids interacted with membranes. Their experiments revealed that certain amino acids bind to membranes and stabilize them. Some amino acids even triggered large structural changes in membranes, such as forming concentric spheres of membranes – much like layers of an onion.
“Amino acids were not just protecting vesicles from disruption by magnesium ions, but they also created multilayered vesicles – like nested membranes,” said lead author Caitlin Cornell, a UW doctoral student in the Department of Chemistry.
The researchers also discovered that amino acids stabilized membranes through changes in concentration. Some scientists have hypothesized that the first cells may have formed within shallow basins that went through cycles of high and low concentrations of amino acids as water evaporated and as new water washed in.
The new findings that amino acids protect membranes – as well as prior results showing that RNA building blocks can play a similar role – indicate that membranes may have been a site for these precursor molecules to co-localize, providing a potential mechanism to explain what brought together the ingredients for life." …